(function(){
    function identify() {
        return this.name.toUpperCase();
    }
    
    function speak() {
        var greeting = "Hello, I'm " + identify.call( this );
        console.log( greeting );
    }
    
    var me = {
        name: "Kyle"
    };
    
    var you = {
        name: "Reader"
    };
    
    identify.call( me ); // KYLE
    identify.call( you ); // READER
    
    speak.call( me ); // Hello, I'm KYLE
    speak.call( you ); // Hello, I'm READER
})();